NIST Gets New Angle on X-Ray Measurements

NIST Gets New Angle on X-Ray Measurements

03/09/2015 11:16 AM EDT

A laser from the NIST-designed autocollimator (square device at top) is beamed at the mirrored polygon in the gray circle at left, and its reflection allows the angle of the polygon’s faces to be precisely determined while the polygon rotates. The black device at bottom takes measurements that minimizes the wobbling the polygon experiences while spinning. Credit: Hudson/NIST View hi-resolution image

Criminal justice, cosmology and computer manufacturing may not look to have much in common, but these and many other disparate fields all depend on sensitive measurements of X-rays. Scientists at the National Institute of Standards and Technology (NIST) have developed a new method* to reduce uncertainty in X-ray wavelength measurement that could provide improvements awaited for decades.
Accurate measurement of X-ray wavelengths depends critically on the ability to measure anglesvery precisely and with very little margin for error. NIST’s new approach is the first major advance since the 1970s in reducing certain sources of error common in X-ray angle measurement.
Many of us associate X-rays with a doctor’s office, but the uses for these energetic beams go far beyond revealing our skeletons. The ability to sense X-rays at precise wavelengths allows law enforcement to detect and identify trace explosives, or astrophysicists to better understand cosmic phenomena. It all comes down to looking very closely at the X-ray spectrum and measuring the precise position of lines within it. Those lines represent specific wavelengths—which are associated with specific energies—of X-rays that are emitted by the subject being studied. Each material has its own, unique X-ray “fingerprint.”
Read more ...